In a study examining dietary intakes of people when first diagnosed with bladder cancer at a major cancer center in New York, researchers found that the patients who ate 1 or more servings/month of raw broccoli versus less than one serving/month had a 43% reduction in death from all causes and a remarkable 57% reduction in death from bladder cancer when looking at data after 8 years of follow-up. Intakes of total vegetables, total fruits, and other cruciferous vegetables did not show any benefits on either overall survival or bladder cancer survival.
Prior animal and in vitro (cell studies) data have shown potent antiproliferative effects of dietary isothiocyanates from cruciferous vegetables on bladder cancer cells. This study was unique because it looked at both raw and cooked food consumption since cooking (especially cooking greens for hours!) can substantially reduce or destroy isothiocyanates contained in cruciferous or Brassica vegetables.
Further follow-up studies with human subjects are clearly warranted but in the meantime, eat your broccoli and other Brassica vegetables, some of them raw, and the rest only very lightly steamed or stir-fried, and save any steaming liquid to use for future soup stock. Of note, although intake of kale and collard greens was evaluated and found to offer no survival benefit in this study, my comment above about the usual cooking technique (i.e., boiling for hours on end) for these vegetables may have rendered their intake inconsequential in this type of study.
Cruciferous vegetables do have a wide variety of glucosinolates, which are metabolized to a wide variety of isothiocyanates that could have different levels of protection against different types of cancers. Eat them all, enjoy them all, in a variety of different ways! And I'm just taking a wild guess, but I'll bet that most regular readers of this blog eat kale, broccoli, and other Brassica vegetables, raw or cooked, more than once a month. :-)
|Photo: Garlic Scape-Kale Pesto - this is not raw broccoli, but a delicious way to eat another raw cruciferous vegetable. Believe it or not (actually I'm embarrassed to admit this), I still have some garlic scapes in my refrigerator (the tops are dried out but the stems are in great shape!), so I'm going to try making this pesto using raw broccoli florets instead of kale. I'll let you know how it turns out!|
Where kale (and broccoli) is more than decoration on my plate!
Diana Dyer, MS, RD